duete; see due, ty 2 ]. syn: duty, obligation refer to something a person feels bound to do. A duty often applies to what a person performs in fulfillment of the permanent dictates of conscience, piety, right, or law: one's duty to tell the truth; a parent's duty to raise children properly.
Mutations in the RB1 gene are responsible for most cases of retinoblastoma. RB1 is a tumor suppressor gene, which means that it normally regulates cell growth and keeps cells from dividing too rapidly or in an uncontrolled way.
Retinoblastoma is a cancer of the retina, the eye's light-sensitive tissue. This most common childhood eye cancer usually strikes children under age five, affecting 500 to 600 in the United States each year. In nearly a third of the cases, retinoblastoma occurs in both eyes. While symptoms are not evident early in the disease, increasing pain and vision loss eventually signal the problem.